When we see a galaxy and a quasar near each other in the sky, it might be because they are really near each other, or it might be that they are far apart and just along the same line of sight. Tests performed by Alan Stockton (Astrophysical Journal 223:747-757, "The Nature of QSO Redshifts", 1978) on a sample of such pairs have shown that some galaxy-quasar pairs have the same redshift and so are accepted as being at the same distance. Other pairs with very different redshifts however have...